[Wien] case.inst and spin orbit interaction

[li wf]

dear wien users,

     i am a new comer and i have some questions here. in the case.inst 
file, what does the occupation number mean? for Zn it has an Ar 3d10 4s2 
configure, but why it can also be discribed as Ne 6 and Ar 3. what do the 3 
and 6 mean? and how to split the electrons into spin-up and spin-down?
     and the last question is to perform a spin-polarized calculation, is 
it necessary to add spin-orbit interaction?
   
    thank you very much.

    best regards,

wane

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